The rubber ring on the front of the lens hood can be carefully taken off, it's just attached via some glue at various points. A small flathead screwdriver and a bunch of time is all it takes.

Then I measured my new hood length and carefully marked it with painters tape and a pencil. Then I used a plastic cutting wheel on a dremel to do the actual cut. After that, just check to make sure you made an even cut, put the rubber ring back on and put a few spots of superglue under the rubber to keep it on.

Looks like it came from the factory.

Crowley. $279. Would cheaper for me to commission you to do the job for me!